Control mechanism



Patented May 21, 1935 v UNITED ISTAT fascists I oonraor. MECHANISM Paul0. Temple,'Decatur, m, m: to a. w. a Cash Company, 'Decatun llL,a,corporation of Delaware Original applica tion May 14,1930, Serial No.

452,434. Divided and this application September 26, 1932, Serial No.834,873

. z Claim.

This invention relates to control mechanism. and more particularly to anapparatus for controlling the speed of a fluid pressure operated motor.This application is a division of my prior application Serial No.452,434 flled May 14, 1930, and issued as Patent Number 1,923,595 onAug.

In the construction of various types of apparatus, such as machine toolsfor example, it is frequently found desirable to utilize fluid pressuremotors for'the operation of the different parts. It is often importantto move such parts at a miform speed, but this result may be diflicultto obtain with prior arrangements, where the pressure of the operatingfluid and the resistance to movement are likely to vary within widelimits. Either an increase in the operating pressure or a decrease inthe resistance tends to cause an un desirable increase in the speed andthus impair the uniformity of the product.

It is accordingly one object of the invention to provide? a fluidoperated motor and associated parts which are so arranged that the speed'of the motor will be held uniform irrespective of variations in theoperating pressure or the resistance to movement.

It is a further object of my invention to providea simple and eilectiveapparatus including a fluid operated motor, which is so arranged thatthe speed of the motor may be conveniently adjusted and will be heldconstant at any desired value. I

p With these and other objects in view, aswill be apparent to thoseskilled in the art, the invention resides in the combination of partsset forth in the specification and covered by the claims appendedhereto.

t In accordance with my invention I provide a motor having an elementwhich is movable under the influence of a fluid pressure, and-I providea confln'ed'body of liquid which resists the-movement of the element.Liquid is allowed to escape from the confined body through a conduitprovided with a valve, and the valve is controlled automatically tomaintain a constant rate of flow.

Referring to the drawings illustrating one embodiment of the invention.and in which like reference numerals indicate'like parts,

Fig. 1 is an elevation of a fluid operated motor and associated certainparts being shown in section for cl or illustration;

' Fig. 2 is a sectional-eievationof the valve mechanisnathe section on.the line 2-; of 1'18. 3? J rigsisasectionontheline ermane (01. izi-aa) 1Fig. 4 is a section on the line 4-4 of Fig. 3.

The embodiment illustrated in Fig. 1 of the drawings comprises acylinder to, a piston l l slid- V able in the cylinder, and a piston rodl2 fastened to the piston. These parts form a motor. The movements ofthe motor piston are controlled by a four-way valve l4, which isconnected to a pipe l5 leading to the upper end of the cylinder, a pipelt'leading two the lower end of the cylinder, to an exhaust pipe l8, andto a supply pipe l9 leading from any suitable supply of fluid underpressure, such as compressed air.

This air of course must be at a sufliciently high pressure to overcomeany resistance encountered by the piston rod. When the valve I4 is inthe position shown, air will flow from supply pipe l9 through pipe l5 tothe upper end of the cylinder,

forcing the piston H to move downwardly. At 7 the same time the airinthe lower end of the cylinder will pass through pipe it to the'exhaustpipe It. If the valve H is turned through 90 degrees in eitherdirection,the lower end of the cylinder will be connected to the supply and theupper end to the exhaust, thus causing upward movement of the piston.The piston rod [2 extends downwardly and is connected to the apparatus(not shown) which is to be operated.

In order to maintain the. speed of thepiston I l constant during itsdownward working stroke, regardless of variations in the air pressure orin the resistance to movement, I preferably provide a second cylinder 20in line with the cylin der Ills The piston red I 2 passes through thecylinder 20 andcarries a second piston 22 which is slidable therein. 20isconnected by a pipe 23 to the inlet of a flow controller 24, and theoutlet of the flow controller is connected by a pipe 26 to an elevatedtank oi reservoir 21 containing a suitable liquid, such as oil.- A pipe28 provided with a valve 30 leads from pipe 23 to pipe 26 and serves asa bypass conduit around theflow control mechanism.

The flow controller 14 may be of any suitable 1 construction which willmaintain a substantially constant rate of flow therethrough. In Figs. 2,3 4.5

a and 4 I have illustratedone arran ement which has proven satisfactoryin actualservice. I This embodiment comprises a casing 32 having aninlet opening 33 and an outlet or discharge opening 34. These openings33 and 34 may be-screwthreaded as shown to facilitate ,the connection ofpipes thereto. .A conduit It leads from the inlet to the outlet,and theflow of liquid in this conduit is controlled by a valve 31, which ispreferably so constructed as to be perfectly balanced ll fluid operated5 The lower end of cylinder 35;

lndheemunalitalhnqtosiidrm' As flnsnlsemaybetmmedasasleevesiidalievuihllyiniheflsing.'Iinvllveismvidedwiihpmtainiismalpufimwhidihdflieliquilinflreintmim-oifllevalvgandwiflionmeddischugepm-isllinhwllatihlolu'mdwhicharevimpedasdnowntogivcthedeiredticaflwn'atimandmmtwirednwingni'flac lipid. Anannnlarpurtllinfliecasingflieslecvcflandisanangcdtowithflie Vpmisll.'ihefiisthevalwedimebbom'abovcandthepmtlland asliikw'ayiorflievalve. miinthevalvewmhewithan andclosedbyat. Asamesultoitheni :ivlflflliflimderthefinidand thuewillbenoforittosiick'andmse'Inurderthatthevalvemaybemtmtedantotomainininatrateoifiowin the,Ipmvidearespmsive devicesuchasapistonlislidahleinthe 32.'Ihispistonispmierabhr valveflamico axialtherewith.Whilethepistonandvalvemaybefmmedinwithothei-Jpretertofoimthemofsepm'ateas 'lmispennitseachparttoheotthemostsuihblematerialandavoidsaserious prohlunint.Apmieciionfllextendsdownwu'diyi'rmnihecmtmlportionofthepistmtotheupperenddthevalve.Thevalveis held against this projection by a canspriigAiwhichbearsagainstaflangeliriveted toflicvalve.AsecondspringlIJargerindiameterflnnsprimllisloeatedbeneaththeItwlllbenotedthatflieeitectotthesetwospfings istobiasthevalve towardopenThe contacting sin-faces oi the'valve andpistimare shaped'to allowrelative movement between thesepartsinadirectiontransversetotheslidingmovementotthevalvesothateventhoughthevaiveandpistonarcoutoialignmenhthepistoncannottransmitlateralstresestothevalveandcauseittobindaxainstthewallofitsslideway. In the embodiment illustrated, theprojection ll isshownwithaplanehorizontalsurfacewhichmntcctswithaconvexsuriaceontheupperendofvalvefl.

In order to obtaina pressure difference for theoperatidnofthepistonlllpreferablyprovidea partition I! which extendsacross the conduit bctweenthe inlet and the outlet, and which has anorifice 5| therein. -.'I'he liquid in flowing through the orifice isreduced in pressure, the pressure diiierence being a function of therate of flow. Itwillbeclear from Fig. 2 that the reduced pressureposterior to the orifice iselfective .sure at the inlet anterior toducted'through a passageway 52 in the casing which leads to the chamber53 above the piston. It will now be seen that the liquid pressuredifi'erence due to the throttling effect of the orifice tends to movethe piston downwardly and close the valve, and that this tendency isopposed by the force oi the springs Whenever the rate of flow increasesto a point slightly above the value for which the mechanism is set, .thepressure drop .across the orifice will likewise increase, the pistonwill move downwardly and close the valve, and normal flow will berestored. If the flow decreases below normaLthe pressure drop willdecrease, the springs will move thepiston upwardly, and the the orificeis conagainst the lower side of the piston. The preswaive wm w n. thusthe rate of M badktoflaedesimd 'lheandvfl 'Matallmammiifimtonninhm theliow,,theliquidprewue diifm iiietwnsidlssofthenisimbeirgmctly hyflneThechamberhelowtihc -k" filledwith Irnflmeansforwalvesoastoa '-'.l w

en-Hana: \r, ml'lymeratedi'or .u thesialenithe El, and the pref ml-w v Hmmmam15l-" :fi fl'nib9 sosstothetoagreateror lesser. ed areobbyfmmingtheeintheshapema Vasshowninlfig i. Thevalveflispmvidedwiflnascrew poriioniiandafl. 'l'ihe stemextends throughabsxflandcarriesahandwheelflonitsouterend. Byturning thehandwheel the valveismoved uto varwthenrifieesize. Thesmailerthee sine, ihedropforarateofflomandhencealowerraieoiflowwillprovide thepressuredroptobaiancetheim'ce oithe.

The operation of the t m inmiisastollows: ethepistms Handilmatihetnpdi'thurrespeciive andtheiowerendotcylinder ilisfilledwithoil. Withvalveilclnsedandvaive ilinihe him shown, com air will enter thenpperendofcyiinder ",cansingihepistonstomovedomwardlyandfomingoilontofcylinder iliheflowcontmllerandbacktothetank 2]. 'Ihe ilowcontmller wm fleshy aconsiantrateofiiomasore ed,regardless of variations in the air crintheresistanceteredbwnistlmrodiiindoingtheworktorwhichitisarranged' 01. course such variations maycausegrutchangesintheplessmeottheoilincylinderltbutthiscannotaifecttheflow.Since oilisincompressiblethespeedotthenmtorwillbedirectlyproportionaltotherateofiiow,andhmcewiilbekeptconsinntasdcsired, even thoughtheload shouldsuddenbbeentirely removed i'rmnthepistonrod. Forrapidreturn movement oi!the pistons upwardly, valve 3! is opened and valve ll turned through SIdegrees. Ollwlllthenflowfromthereservoirflthrough nine 23, by-passingthe controller, and permittingcylinderzltoflllquickly. Bypropermanipulation of .valve 3|, the downward movementmayberapiduptoanydesiredpoint. Assooo, as valve 3| is closed, the flowcontroller will become elfective and a desired constant speedmaintained.

Having thus described my invention, what Iclaimasnewanddesiretosecurebylletters Patentis:

1. The combination of a motor having a reciprocable element, meansto'apply fluid under pressure to the element to move the same in eachdirection, a cylinder, a piston slidable in the cylinger, meansconnecting the piston with the reciprocable'element, the cylinderserving to conline a body of liquid which'resists movement of the pistonin one direction, a reservoirfor liquid located at a higher elevationthan said cylinder, a conduit connecting the cylinder with thereservoir, a valve in the conduit, means providing a restriction in theconduitto create a pressure differential which is a function of the rateof 75 flow in the conduit, means responsive to changes in said pressuredifierential and arranged to actuate the valve and maintain saidpressure differential substantially constant, a by-pass conduit aroundthe valve, and a valve in the by-pass conduit. 2. The combination of twoaxially aligned cylinders, a piston slidable in each cylinder, a pistonrod connecting the pistons, means to admit fluid under pressure toeither end of one cylinder and thus move the pistons and piston rod ineach direction, the other cylinder serving to confine a body of liquidwhich resists movement of the pistons and piston rod in one direction, areservoir for liquid located at a higher elevation than said othercylinder, a conduit connecting said other cylinder with the reservoir, avalve in the conduit, means providing a restriction in the conduit tocreate a pressure differential which is a function of the rate of flowin the conduit, means responsive to changes in said pressuredifferential and arranged to actuate the valve and maintain saidpressure differential substantially constant, a by-pass conduit aroundthe valve, and a valve in the by-pass conduit.

PAUL C. TEMPLE.

